A unified data center structure is a network structure that combines the traditional local area network (LAN) and the storage area network (SAN) in the same physical network so as to reduce the structure complexity and strengthen the data flow and visit. In order to bring it into effect, the traditional Ethernet must be upgraded as “no-losing”, and provide extra characteristic and function of the data center network. Therefore, the storage protocol must be adjusted so as to run on the Ethernet.
The institute of electrical and electronics engineers (IEEE) has already defined the term, data center bridging (DCB), which is an framework set expanded from the Ethernet and designed to improve the Ethernet and data center management. The DCB is also called as Converged Enhanced Ethernet (CEE), Data Center Ethernet (DCE) (the brand owned by Cisco), Enhanced Ethernet for Data Center (EEDC), and the like.
At present, in the DCB group, a requirement on an edge virtual bridging (EVB) of a virtual environmental network is proposed, that is, for a physical terminal site, it includes a plurality of virtual terminal sites, and each virtual terminal site requires to have the services of accessing the neighbor bridges of the LAN. In the EVB environment, a network adapter (network interface card, NIC) has a plurality of virtual network adapters (vNICs), and each vNIC can communicate with the bridge in the EVB independently, and those a plurality of vNICs share a link. In order to realize that function, the DCB group has proposed a port extension mode. That is, the ports of an interchanger connecting to a plurality of sites can be realized through the Port Extension (PE); if that PE is embedded into the server, then the ports of an interchanger connecting to a plurality of virtual terminal sites (Virtual Machine, VM) can be realized and the communication among them is realized through the interchanger, and the interchanger here is called the controlling bridge (CB).
In order to realize this kind of port extension, the services transmitted on the virtual sites need to be isolated, and the method adopted at present is to introduce a new tag (E-tag), to establish a plurality of channels (E-Channel) between the controlling bridge and the site, thus realizing the isolation of the services, as shown in FIG. 1. Each message coming out from the controlling bridge will be carried with one E-tag by the controlling bridge, and the PE will send that message to the correct egress port according to the E-tag value of that message. Therefore, the controlling bridge is required to be able to configure the port of the PE with the E-tag member set and the untagged set, to realize normally forwarding the message carrying the E-tag by the PE. The corresponding message commands are already provided in the standard at present, the downlink port of the PE sends the Extended Port Create message to ask for assigning the E-tag, the controlling bridge replies to that port with one E-tag, and the PE adds that port into the member set and the untagged set corresponding to that E-tag after receiving it. If there is a cascade PE, such as PE1 in FIG. 1, between that PE, such as PE2, and the controlling bridge, then the controlling bridge further needs to send E-channel register message to the port of the PE1 connected to the PE2, and the PE1 adds that port into the member set of that E-tag after receiving the message.
Therefore, for the controlling bridge, it should first clearly understand the situation of the PE connected to the controlling bridge itself, each port of the PE, and the connection relations among the ports, that is, the topology. There is no method for specifically acquiring the topology of each connected PE at present.